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Fire Dive Gear - underwater fluorescence photography equipment

Fluorescence
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#21 Cadmium

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Posted 10 March 2020 - 02:17

I forgot to add that one reason the actinic lights may make the card look more 'normal' is because although the actinic light peaks at 455nm, those generally also have a little of everything else in the visual range too.
graphs:
https://www.google.c...iw=1920&bih=925

#22 Stefano

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Posted 10 March 2020 - 02:30

My last post here https://www.ultravio...os/page__st__80 is about the same thing. The exitation wavelength is important.

Edited by Stefano, 10 March 2020 - 02:32.


#23 Stefano

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Posted 10 March 2020 - 02:38

Also, white fluorescence under blue light is strange (shouldn't be possible I think). Conventional fluorescence converts the exitation light to light with a longer wavelength (Stokes shift), so you should be getting yellow fluorescence+reflected blue (like white LEDs). Thinking about LEDs, what about the new ones that use a violet or even ultraviolet "pump"? Unlike CFLs, the only light exiting the phosphor is violet-UV, and they produce white light. Could be interesting to try that out.

Edited by Stefano, 10 March 2020 - 05:21.


#24 dabateman

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Posted 10 March 2020 - 04:10

View PostAndy Perrin, on 10 March 2020 - 02:07, said:


3) We need some actual info on which wavelengths flowers fluoresce best under.

What fluorescence do you want?
For induced IR fluorescence, a 450nm peak light is great. I like using 405nm LED or BG39 filtered white LED.
Mark had some great photos with a cyan, approximately 488nm light source.
The Visible induced fluorescence looks best under 365nm. But saying that I haven't played with a 385nm LED and that might be better/different/worst. Don't know. I may add that light to my 365nm and 405nm leds.
Amazon does have cheap 385nm E27/E26 bulbs.

#25 Cadmium

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Posted 10 March 2020 - 04:46

David, The Cyan light that Mark uses is for IR fluorescence, which is the standard excitation for IR fluorescence. The 356nm also works obviously, but the old standard is green/cyan to induce IR fluorescence.
I don't know if Mark has used the cyan for any visual range florescence or not.

What Lynn is saying is that visual fluorescence looks better using 455nm, for bio-florescence, but I am not clear if that is simply because of being underwear or more to do with the sea life itself.

https://firedivegear...UV-rev1.doc.pdf
Reading that link, he explains the best wavelength, and also talks about Charles Mazel who worked on determining which wavelength(s) of light cause the greatest spectral emission of sea creatures.

Here is a page and a video about Charles Mazel:
https://oceanexplore...el/welcome.html

His Nightsea page:
https://www.nightsea.com/

Interesting stuff here:
https://www.nightsea.com/resources/#

Edited by Cadmium, 10 March 2020 - 05:26.


#26 colinbm

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Posted 10 March 2020 - 06:03

Great collection of links Thanks Steve

#27 Andy Perrin

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Posted 10 March 2020 - 19:18

View Postdabateman, on 10 March 2020 - 04:10, said:

What fluorescence do you want?
For induced IR fluorescence, a 450nm peak light is great. I like using 405nm LED or BG39 filtered white LED.
Mark had some great photos with a cyan, approximately 488nm light source.
The Visible induced fluorescence looks best under 365nm. But saying that I haven't played with a 385nm LED and that might be better/different/worst. Don't know. I may add that light to my 365nm and 405nm leds.
Amazon does have cheap 385nm E27/E26 bulbs.
What I'm really asking is what is your basis for saying things like "the visible fluorescence looks best under 365"? Has anyone tested this systematically for a variety of species under a variety of excitation wavelengths and tabulated something like overall brightness?

Edited by Andy Perrin, 10 March 2020 - 19:22.


#28 dabateman

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Posted 10 March 2020 - 19:56

I also don't think I was clear.
If we assume visible light is 400nm to 700nm. Then what are you looking for? Blue is roughly 400nm to 500nm. So you can't use a 455 or 488nm light source to get blue fluorescence, unless you have a tight cut filter.
Look at my salad series. There was blue and red and little green depending on the vegetable.
This is why I said I like 365nm. I have a 405bp10 filter, which I have imaged with my 405nm light source, and didn't like the visible fluorescence for the one subject I tested.
I haven't tested a 385nm led light, but with a U340 filter, that might produce an excellent fluorescence range into the visible.

#29 Andy Perrin

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Posted 10 March 2020 - 20:33

Sure, but you could test systematically from 300nm excitation down to 400nm and tabulate overall brightness of the fluorescence. The point is to be systematic and not haphazard. You make a little table:

Species name
excitation wavelength | brightness (400-700nm)
300 nm | ???
320 nm | ???
...

like that for a bunch of species. Then you compare the results.

#30 Stefano

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Posted 10 March 2020 - 21:48

How do you define which one looks best? Since colors change depending on the exitation wavelength, there isn't a "right" wavelength, but since 365 nm is a standard, well-known UVA wavelength, it can be used as the wavelength of reference for UVIVF. (I couldn't avoid writing "wavelength" so much).

#31 Andy Perrin

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Posted 10 March 2020 - 21:56

I was using "brightness" as the measure, not some kind of image quality, Stefano. I don't know how you would quantify "best" either.

#32 Stefano

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Posted 10 March 2020 - 21:59

Probably deep UV is absorbed more and you have less fluorescence there... but someone needs to test it.

#33 dabateman

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Posted 10 March 2020 - 22:17

View PostStefano, on 10 March 2020 - 21:59, said:

Probably deep UV is absorbed more and you have less fluorescence there... but someone needs to test it.

Nope I need food. I don't need this test.
I think we should just switch over to using Colin's new 365/375/385/395nm led quad head and hit with all the good UV-A wavelengths. Filter that with a U340 and your all set.


#34 Stefano

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Posted 10 March 2020 - 22:20

I would use U-360 for this LED, to avoid reducing the 395 nm wavelength too much.

#35 Andy Perrin

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Posted 10 March 2020 - 22:53

Heh, I guess just hitting it with every damn UV wavelength would probably be best. Then you get everything, right?

#36 Stefano

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Posted 10 March 2020 - 22:56

View PostAndy Perrin, on 10 March 2020 - 22:53, said:

Heh, I guess just hitting it with every damn UV wavelength would probably be best. Then you get everything, right?
Yes, you should. Things can only add up, not subtract.

#37 Cadmium

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Posted 11 March 2020 - 08:34

This dive card, and the guy that makes it, and my conversations with him, quite frankly have challenged my basic foundation for my long time assumption that 365nm was THE band to use for fluorescence.
Prior to that I just thought any old 'black light', which usually has a much wider band reaching down to 320nm and up into the visual range (not sure how far up).
But after spending time here, for years, a decade or so, I have come to believe and advise narrow 365nm as being THE optimal excitation for UVIVF.
Now suddenly I am asking why. Where did I get that? I got it here. Then why do we say that? Where did that come from?
That certainly is NOT the band that marine biologists use. They don't use UV at all, they optimally use 455nm, with barrier filters that go with that.
Here: As to using UV vs. 455nm, the marine research community has gotten away from UV a couple decades ago because it is very inefficient, provides poor results and is very harmful to the eyes of the creatures (that have eyes) causing - in most cases, permanent blindness.
Perhaps the inefficiency is simply due to the water filtering out much of the UV/violet, and that would then make scence given the narrow 365nm, but I don't know that is the reason exactly or entirely.
Certainly causing damage to life is not good.
The things is, it would behoove us to pin down exactly the reason for what we think, and the reasons for what the Marine community thinks and uses, the exact reason for each thinking,
because we want to be all inclusive here and I think we want to understand both situations so we can expand our thinking and advise those who are doing things different than we are.
This is something we need to figure out.

Edited by Cadmium, 11 March 2020 - 08:40.


#38 colinbm

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Posted 11 March 2020 - 09:36

Because different things are excited to fluoresence at different wavelengths.
OK you have found that the dive industry like to use 455nm.
Mineralogists use shortwave, midwave & longwave UV to excite minerals.
Then there is the cyan 500nm induced IR fluorescence.
The only optimum is what has been before & researched.
Biologist seem to like to get the nice blue/cyan into the picture too....?
What floats your boat I guess...?
Yeah it would be a long list.

Edited by colinbm, 11 March 2020 - 09:36.


#39 Stefano

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Posted 11 March 2020 - 10:31

I think that 365 nm is a standard, and if you want to standardize results, you should use this wavelength. Of course, the more wavelengths you use, the more information you have, the better. There is no point in asking what is the correct wavelength, all are equally valid. It is like asking if 360 nm UV should be rendered as yellow and 390 nm as blue-violet, or if LWIR must be rendered white-hot, rainbow, iron or with other color palettes (Andy and I had a discussion about this here https://www.ultravio...__fromsearch__1). It is a very complicated thing to handle.

#40 JMC

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Posted 11 March 2020 - 10:52

Steve, strangely enough I've been thinking about the question of fluorescence recently. The skin research world uses UVA induced fluorescence a lot to look at skin dryness, and also bacterial presence, and melanin formation and distribution. Dermatologists used to use Woods lamps with 365nm fluorescent tubes for this, but there is a move now to more use of LEDs. One of the manufacturers of skin research equipment, has recently moved from a small fluorescent tube to LEDs, and have shifted their wavelength from 365nmish up to about 385nm.

Then at the other end of the scale is the use of 295nm light sources, to look for fluorescence at 340nm - UV induced UV fluorescence. Obviously under very controlled exposure.

There is also one manufacturer of equipment that uses a Cyan light source, to look for fluorescence in the green and orange regions.

It really is 'horses for courses' as they say.

I do agree though with something you said, that we should not be causing damage to creatures that we are imaging (if we are imaging creatures).
Jonathan M. Crowther

http://jmcscientificconsulting.com